非线性Lipschitz连续算子的定量性质(Ⅲ)──glb-Lipschitz数

本文引进非线性Ｌｉｐｓｃｈｉｔｚ算子Ｔ的ｇｌｂ－Ｌｉｐｓｃｈｉｔｚ数ｌ（Ｔ）,并证明：ｌ（Ｔ）定量刻画非线性Ｌｉｐｓｃｈｉｔｚ连续算子全体所构成的赋半范算子空间中可逆算子Ｔ保持可逆的最大扰动半径,因而具有特别重要意义。所获结果被应用来建立“非线性扰动引理”、非线性算子条件数、推广线性算子逼近理论和建立与矩阵理论中Ｇｅｒｓｃｈｇｏｒｉｎ圆盘定理对应的非线性Ｌｉｐｓｃｈｉｔｚ连续算子谱集的包含域。     

A NOTE ON RECURRENT SETS

ＡＮＯＴＥＯＮＲＥＣＵＲＲＥＮＴＳＥＴＳ￥ＷＥＮＺＨＩＹＩＮＧ；ＷＵＬＩＭＩＮＧ；ＺＨＯＮＧＨＯＮＧＬＩＵ（ＤｅｐａｒｔｍｅＤｔｏｆＭａｔｈｅｍａｔｉｃｓ，ＷｕｈａｎＵｎｉｖｅｒｓｉｔｙｓＷｕｈａｎ４３００７２，Ｃｈｉｎａ．）Ａｂｓｔｒａｃｔ：Ｔｈｅ...     

一类修正的Szasz－Kantorvich算子与Baskakov－Kantorovich算子的逼近定理

该文利用三对角无穷方阵修正Ｓｚａｓｚ－Ｋａｎｔｏｒｖｉｃｈ（以下简记Ｓ－Ｋ）算子与Ｂａｓｋａｋｏｖ－Ｋａｎｔｏｒｏｖｉｃｈ（以下简记Ｂ－Ｋ）算子．对于这两类修正的算子，我们得到了Ｈ．Ｈｅｒｅｎｓ和Ｇ．Ｇ．Ｌｏｒｅｎｔｚ型的结果以及在Ｌｐ（０）中逼近的正逆定理。     

C~m空间中非线性Lipschitz连续算子的定量性质

在有限维复Ｂａｎａｃｈ空间Ｃｍ中,全体Ｌｉｐｓｃｈｉｔｚ连续算子构成一赋半范的非线性算子空间Ｌ（Ｃｍ）．本文研究Ｌ（Ｃｍ）中非线性算子的定量性质,包括：Ｌ（Ｃｍ）中可逆算子到不可逆算子集合的逼近距离、Ｌ（Ｃｍ）中算子乘幂压缩的逆问题以及Ｌ（Ｃｍ）中算子的数值值域与谱集的联系,文中所得结果推广了线性算子理论中许多著名结论．     

一类修正的Szasz—Kantorvich算子与Baskakov—Kantorovich算子的逼近定理

该文利用三对角无穷方阵修正Ｓｚａｓｚ－Ｋａｎｔｏｒｖｉｃｈ（以下简记Ｓ－Ｋ）算子与Ｂａｓｋａｋｏｖ－Ｋａｎｔｏｒｏｖｉｃｈ（以下简记Ｂ－Ｋ）算子。对于这两类修正的算子，我们得到了Ｈ．Ｈｅｒｅｎｓ和Ｇ．Ｇ．Ｌｏｒｅｅｎｔｚ型的结果以及在Ｌｐ（０）中逼近的正逆定理。     

本质正规算子的模小紧相似

本文证明了一类本质正规算子Ａ＇（Ω＇;１）（Ｔ∈Ａ＇（Ω＇;１）,如果Ｔ满足（１）Ｔ,Ｔ｜Ｈ（Ｔ）分别是本质正规算子;（２）σ（Ｔ）＝Ω,ρＦ（Ｔ）∩σ（Ｔ）＝Ω;（３）ｉｎｄ（Ｔ－λ）＝－１,ｎｕｌ（Ｔ－λ）＝０,λ∈Ω＇;（４）σ（Ｔ｜Ｈ（Ｔ））是一完全集,这里Ω＇是一连通的解析Ｃａｕｃｈｙ域, Ｈｌ（Ｔ）＝ Ｖ｛ｋｅｒ（Ｔ－λ）＊：λ∈ρｒｓ－Ｆ（Ｔ）｝是模小紧相似的．     

Banach空间中线性算子的Tseng度量广义逆

在 Ｂａｎａｃｈ空间中,利用 Ｂａｎａｃｈ几何方法及度量投影算子,将 Ｅ．Ｈ．Ｍｏｏｒｓ的学生,曾远荣（Ｙ．Ｙ． Ｔｓｅｎｇ）在 Ｈｉｌｂｅｒｔ空间中为线性算子引入的 Ｔｓｅｎｇ广义道,推广到 Ｂａｎａｃｈ空间,引入 Ｔｓｅｎｇ度量广义逆（此时的 Ｔｓｅｎｇ度量广义逆一般为齐性算子,而非线性算子）,利用 Ｂａｎａｃｈ空间对偶映射与广义正交分解定理给出 Ｔｓｅｎｇ度量广义道存在的充分必要条件．讨论了最大Ｔｓｅｎｇ度量广义逆在最优化,控制论及微分方程不适定问题有着直接应用的一些基础性质．     

AVERAGE σ-K WIDTH OF CLASS OF Lp（R^n） IN Lq（R^n）

ＡＶＥＲＡＧＥ　σ－Ｋ　ＷＩＤＴＨ　ＯＦ　ＣＬＡＳＳ　ＯＦ　Ｌ_ｐ（Ｒ~ｎ）ＩＮ　Ｌ_ｑ（Ｒ~ｎ）ＡＶＥＲＡＧＥσ－ＫＷＩＤＴＨＯＦＣＬＡＳＳＯＦＬ_ｐ（Ｒ~ｎ）ＩＮＬ_ｑ（Ｒ~ｎ）￥ＬＩＵＹＯＮＧＰＩＮＧＡｂｓｔｒａｃｔ：Ｔｈｅａｖｅｒａｇｅσ－Ｋｗｉｄｔ...     

Black-Scholes微分方程的必要条件(Ⅰ)

我们知道,著名的Ｂｌａｃｋ－Ｓｃｈｏｌｅｓ微分方程是根据资产价格行为服从对数布朗运动导出来的,假设资产价格Ｓ服从对数布朗运动,即有这里Ｗ为标准布朗运动,σ为Ｓ的波动率,ｒ为无风险收益率,σ和ｒ均为常数．欧式看涨期权的价格函数　（ｔ,ｘ）则满足这里而Ｔ为有效期限,Ｋ为敲定价格,ｂ．,ｂ＊分别为期权敲出的资产价格对数下限、上限（只要资产价格对数高于ｂ＊或低于ｂ．,就把期权敲出）．由此可知,式（１）是Ｂｌａｃｋ－Ｓｃｈｏｌｅｓ微分方程（式（２））成立的充分条件．现在．我们通过分析式（２）的性质,来探索…     

A law of the iterated logarithm for processes with independent increments

ＡＬＡＷＯＦＴＨＥＩＴＥＲＡＴＥＤＬＯＧＡＲＩＴＨＭＦＯＲＰＲＯＣＥＳＳＥＳＷＩＴＨＩＮＤＥＰＥＮＤＥＮＴＩＮＣＲＥＭＥＮＴＳＷＡＮＧＪＩＡＧＡＮＧ（汪嘉冈）（ＥａｓｔＣｈｉｎａＵｎｉｖｅｒｓｉｔｙｏｆＳｃｉｅｎｃｅ＆Ｔｅｃｈｎｏｌｏｇｙ,Ｓｈａｎｇ...     

The Quadratic Numerical Range of an Analytic Operator Function

We introduce a new concept of numerical range for analytic operator functions. This so-called quadratic numerical range is induced by a decomposition of the underlying Hilbert space. Like the classical numerical range of an operator function, it is not convex, it has the spectral inclusion property, and it provides resolvent estimates and estimates for the lengths of Jordan chains in boundary points having the exterior cone property. As the quadratic numerical range is contained in the numerical range, it yields tighter enclosures for the eigenvalues and the spectrum of analytic operator functions.     

Numerical range of operators acting on Banach spaces

The aim of the paper is to propose a definition of numerical range of an operator on reflexive Banach spaces. Under this definition the numerical range will possess the basic properties of a canonical numerical range. We will determine necessary and sufficient conditions under which the numerical range of a composition operator on a weighted Hardy space is closed. We will also give some necessary conditions to show that when the closure of the numerical range of a composition operator on a small weighted Hardy space has zero.     

Hamilton算子的一类n次数值域的对称性

以Hamilton算子的数值域为基础,研究了一类算子的二次数值域关于实轴,虚轴的对称性.此外从α-J-自伴算子的n次数值域关于过原点直线对称出发,得到了有界Hamilton算子的一类n次数值域关于虚轴的对称性.     

On the Origin and Numerical Range of Bounded Operators

Numerical range has an important applications on spectrum distribution of operators. In this paper, we devoted to characterizing operators whose numerical range contains the origin. Some necessary and sufficient conditions are given by operator decomposition technique and constructive methods. Furthermore, the closeness of the numerical range of a given operator is also investigated.     

无穷维Hamilton算子的二次数值域

研究了一类无界无穷维Hamilton算子的二次数值域的性质,进而,应用二次数值域来刻画了无穷维Hamilton算子谱的分布范围,并给出了二次数值域的闭包包含谱集的结论.     

Product numerical range in a space with tensor product structure

We study operators acting on a tensor product Hilbert space and investigate their product numerical range, product numerical radius and separable numerical range. Concrete bounds for the product numerical range for Hermitian operators are derived. Product numerical range of a non-Hermitian operator forms a subset of the standard numerical range containing the barycenter of the spectrum. While the latter set is convex, the product range needs not to be convex nor simply connected. The product numerical range of a tensor product is equal to the Minkowski product of numerical ranges of individual factors.     

A new concept for block operator matrices:the quadratic numerical range

In this paper a new concept for 2×2-block operator matrices – the quadratic numerical range – is studied. The main results are a spectral inclusion theorem, an estimate of the resolvent in terms of the quadratic numerical range, factorization theorems for the Schur complements, and a theorem about angular operator representations of spectral invariant subspaces which implies e.g. the existence of solutions of the corresponding Riccati equations and a block diagonalization. All results are new in the operator as well as in the matrix case.     

无界分块算子矩阵的谱分布

本文首先给出次对角元有界的2×2阶无界算子矩阵的Gershgorin定理,然后利用主对角元算子的谱和数值域刻画整个算子矩阵的谱分布.特别地,当次对角元算子互为共轭(反共轭)算子时,结合二次数值域和Gershgorin定理对谱分布给出更精细的描述.     

Remarks on numerical ranges of operators in spaces with an indefinite metric

The numerical range of an operator on an indefinite inner product space (possibly infinite dimensional) is studied. In particular, operators having bounded numerical ranges are characterized, and the angle points of the numerical range and their connections with eigenvalues are described.

     

Birkhoff's theorem and multidimensional numerical range

We show that, under certain conditions, Birkhoff's theorem on doubly stochastic matrices remains valid for countable families of discrete probability spaces which have nonempty intersections. Using this result, we study the relation between the spectrum of a self-adjoint operator A and its multidimensional numerical range. It turns out that the multidimensional numerical range is a convex set whose extreme points are sequences of eigenvalues of the operator A. Every collection of eigenvalues which can be obtained by the Rayleigh-Ritz formula generates an extreme point of the multidimensional numerical range. However, it may also have other extreme points.